The use of shock waves to treat various conditions affecting the bone or soft tissues of a mammal, usually a human is known.
Shock waves produce a high energy pulse that when focused can pulverize hard calcium deposits such as kidney stones. This technology is commonly and very successfully employed in lithotripsy.
More recently, the use of shock waves has been employed in the art of healing non union bone fractures and in treating soft tissues and organs extracorporeally in a non-invasive manner.
The pressure pulse or wave form when applied was thought to require a high energy to achieve a deep penetration to an affected organ, as a result focused beams were transmitted that had a focal point or region set at a distance deep enough to penetrate the underlying organ or tissue. It was believed that the skeletal system of hard bone mass greatly dampened the wave pattern making it difficult to treat such organs as the heart.
In U.S. Pat. No. 6,755,821 B1 entitled “A System and Method for Stimulation and/or Enhancement of Myocardial Angiogenesis” a proposed solution to treating the heart using shock waves was proposed. Shock-waves were applied using a combination lithotripsy probe/balloon system, comprising a needle and cannular balloon which can be inserted through the skin at a point between the ribs into the cavity beneath the chest wall and overlying the heart. Alternatively, the shock-wave can be administered extracorporeally or via a catheter. A fluid injector was connected to the balloon, allowing it to be inflated with saline or other appropriate fluid to fill the space (for transmission of shock waves and/or to displace tissue—such as lung) and contact the surface of the heart. A shock-wave (acoustic) generator was used to generate shock-waves through the lithotripsy probe, through the fluid and into the myocardial tissue. The fluid provides a uniform medium for transmission of the acoustic energy, allowing precise focus and direction of the shock-wave to induce repeatable cavitation events, producing small fissures which are created by the cavitation bubbles. In this case, channels would not be ‘drilled’ into the heart muscle, minimizing trauma to the tissue while still creating conditions that will stimulate increased expression of angiogenic growth factors.
The concept in U.S. Pat. No. 6,755,821 provides an alternative to procedures in place today that rely on lasers. As stated in the above referenced patent.
“Transmyocardial revascularization (TMR) using a laser (sometimes referred to as TMLR, LTMR, PMR, PTMR, or DMR) has been developed over the past decade, initially by a company called PLC Systems, Inc., of Franklin, Mass. PLC's system utilizes a high power (800-1000 W) carbon dioxide (CO.sub.2) laser which drills small channels in the outside (epicardial) surface of the myocardium in a surgical procedure. The holes communicate with the left ventricle, which delivers blood directly to the heart muscle, mimicking the reptilian heart. Many other companies are developing laser TMR systems, most introducing the laser light via optical fibers through a flexible catheter, making the procedure less-invasive. These companies include Eclipse Surgical Technologies, Inc., of Sunnyvale, Calif., and Helionetics, Inc., of Van Nuys, Calif. The Eclipse TMR system uses a Ho:YAG laser with a catheter-delivered fiber optic probe for contact delivery to the myocardium. The Helionetics system is based on an excimer laser. In addition to the holmium:YAG and excimer lasers, and other types of lasers have been proposed for TMR.
While the channels created during TMR are known to close within 2-4 weeks, most patients tend to improve clinically over a period of 2-6 months.
Such clinical improvement may be demonstrated by reduction in chest pain (“angina”), and a dramatic increase in exercise tolerance (“ETT”, or treadmill test). The mechanism of laser TMR is not fully understood, but it is postulated that the laser causes near-term relief of angina through denervation or patent channels, with subsequent long-term clinical improvement due to angiogenesis, i.e., growth of new blood vessels, mainly capillaries, which perfuse the heart muscle. These new “collateral” vessels enable blood to reach downstream (“distal”) ischemic tissues, despite blockages in the coronary arteries. Some of the possible mechanisms by which the laser induces angiogenesis could include activation of growth factors by light, thermal, mechanical, cavitational or shockwave means. In fact, all lasers which have been successfully used for TMR are pulsed systems, and are known to create shock waves in tissue, and resulting cavitation effects.”
The problem of delivery of a shock wave to an internal organ is more complex than simply avoiding bone tissue. In the case of treating the heart special care must be taken to avoid damaging the thin membrane of the nearby lung. Shock waves inadvertently transmitted to this area can cause bleeding and other damage.
Another problem for the use of shock waves is internal organs are three dimensional masses that in the case of the heart need the waves to be directed from two sides front and back, more preferably from at least three directions.
Accordingly the devices such as the laser or the shock wave system of U.S. Pat. No. 6,755,821 are limited to one surface of the heart or would require multiple points of entry.
The team of inventors of the present invention has developed both a device and a methodology for treating an internal organ which addresses these limitations and provides a multiple direction system for delivering shock waves.